The Appendix: It’s Not as Useless as You’ve Been Told

What thoughts spring to mind when you think about your appendix? Probably not very much. Perhaps you or someone you know has had theirs removed. People will tell you that you won’t miss it at all. My whole life I believed that the appendix probably had some use and that we just hadn’t found out yet. It turns out I was right; some interesting research has recently been published demonstrating that the appendix has a function after all.

So what exactly is the appendix? Well, the appendix, or ‘vermiform appendix’ as it is properly called, is a small tube like organ located near the junction of the large and small intestines. Its name is kind of funny, in a descriptive sort of way. Translated from Latin, vermiform literally means ‘worm shaped’ (check out a picture and you’ll see the description is spot on). The appendix is hung onto the digestive system, but, much like the appendix (or appendices) of a book, the casual observer would fail to notice it.

So what does our little worm shaped friend the appendix do? Well, scientists have recently discovered that the appendix may act like a safe house for good bacteria in your gut.

In case you didn’t know, your body (both inside and outside) is the home to a myriad of bacteria… a lot of bacteria. In fact, the Human Microbiome Project (funded by the U.S. National Institutes of Health) estimates that the average person is host to around 100 trillion bacteria1. It may sound a bit icky, but you want these guys sticking around.

Having a thriving community of gut bacteria is very important for your health—and it turns out that this relationship is mutually beneficial. Among other things, gut bacteria aid in digestion, reduce harmful substances in the body, stimulate cell growth in the gut, and inhibit the growth of harmful bacteria. What the bacteria get in return is food. Our large intestine is sort of like a bacteria cafeteria. As long as we are eating, our little friends are being supplied with food as well.

However, as many of us know, the figurative sun does not always shine in our digestive system. For example, when someone gets diarrhea due to a disease or some other cause, bacteria is literally flushed from your gut. Afterwards, your intestine will inevitably be repopulated with bacteria again. While it is very difficult for all of your ‘good’ intestinal bacteria to be wiped out by one bout of diarrhea, many third world countries suffer from endemic diarrhea, which makes it much more likely for the ‘good’ bacteria to be cleaned out almost completely2. This is where the danger arises. It is possible for other types of ‘bad’ bacteria to populate your intestine before the ‘good’ bacteria have time to reestablish themselves. If this occurs, you may end up with a type of pathogenic e. coli, which can be deadly.

That’s where the appendix comes in. It provides a safe place for some ‘good’ bacteria to hide while the diarrhea (pardon my French), runs its course. Afterwards, these bacteria are ready to move out of the appendix and help repopulate the gut; as mentioned above, this will also help to inhibit the growth of dangerous bacteria.

A study recently conducted at Winthrop-University hospital put this idea to the test by examining patients who had been infected by Clostridium difficile (C. diff). C. diff is a bacteria that patients with little gut bacteria (due to illness or strong antibiotics) often catch in hospitals3.  Each year, it is responsible for the death of 14,000 people in America alone4. For the study, the researchers tracked two groups of patients, those who had functioning appendices, and those who’d had their appendices removed. They found that patients who had no appendix were more than twice as likely to suffer a recurrent infection of C. diff.

The appendix, as it turns out, could save your life. That makes it a lot more important than we have traditionally believed—for example, Charles Darwin purposed that ancient humans used the appendix to digest leaves; but as our diets changed and we evolved the appendix shrunk down to a useless ‘vestigial’ organ5.
These discoveries about the function of the appendix just go to show that nothing in our bodies is without a purpose or use. God designed everything with a purpose; sometimes we simply fail to see or understand what is happening in the world around us.

Now, the purpose of this article is not to say that you shouldn’t get your appendix removed if you come down with appendicitis. The immediate danger of dying from appendicitis far outweighs the risk of infection later in life.

Let’s end with an amazing fact. Do you know how much bacteria your gut actually contains? In case you find it difficult to picture trillions of bacteria, I’ll leave you with a quote from Lita Proctor the director of the Human Microbiome Project. “The gut is not jam-packed with food; it is jam-packed with microbes…Half of your stool is not leftover food. It is microbial mass6.”


1 “100 Trillion Good Bacteria Call Human Body Home.” SFGate.

2 “Appendix Isn’t Useless At All: It’s A Safe House For Good Bacteria.” ScienceDaily.

3 McKie, Robin. “Is the Mystery of the Appendix Close to Being Unravelled?” The Guardian.

4 “Bugs in the System.” The Economist.

5 McKie, Robin. “Is the Mystery of the Appendix Close to Being Unravelled?” The Guardian.

6 Kolata, Gina. “Human Microbiome Project Explores Our 100 Trillion Good Bacteria.” The New York Times.

Jon Ewald, MD

Jon Ewald grew up in Minnesota and has a love for the outdoors. He obtained his medical degree at Loma Linda University, graduating in 2020. He is currently completing his residency in Radiology at University of Pittsburgh.

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